The use of Ultrasound to determine rheological properties
22/10/2008
The development of household products is becoming increasingly complex as consumers become more demanding in the long term quality and functionality of the products. In seeking to produce products with specific storage, dispensing and application properties, one of the key properties is the flowability.
Rheology is a measure of the time-temperature-dependent flow and deformation properties of liquids and deformable solids under an applied force.
Polymers and plastics industries are the largest users of these techniques for deformable solids. Significant use is also made in the analysis of oil and lubricant where viscosity is the most critical aspect of product performance.
With the need to reduce waste and improve the control of processes, industry needs to produce rheological data in real time. Currently methods, of making in-line rheological measurements are challenging as it is difficult to integrate conventional rotational instruments into a process stream.
While such mechanical technology can be adapted to on-line measurements they are not suitable for samples where flow rate modifies the behaviour, conventional instrument are also unsuitable for pipeline operations where cost, size, dependability, reliability, and ease of integration into control systems is an issue.
Ultrasonic Spectroscopy (USS) is the characterisation of the thermo physical properties of materials and measures the response to a High frequency Mechanical wave. Hence ultrasound can be used as a measure the rheological properties of a material. Specifically the attenuation and velocity information can be used to determine the longtitudinal bulk modulus of a material.
Where k is the ultrasound wave number ω is the angular velocity ρ and M the longtitudinal modulus.
* denotes complex values.
ITS has developed an Ultrasonic Spectroscopy instrument the m3000u USS which is capable of providing attenuation and velocity information on liquids and soft solids.
For more information about particular applications or the m3000u instrument, please contact:
Richard Tweedie
E: richard.tweedie@itoms.com
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